<template>
  <div class="app-container">
    <el-dialog
      v-loading="loading"
      :visible.sync="dialogSeeVisible"
      :title="dialogTitle"
      :close-on-click-modal="closeModel"
      modal
      width="80%"
      @close="closeDialog"
      @open="onOpen"
    >
      <el-card class="cpdf">
        <div class="center">
          <div class="contor">
            <el-button @click="prev">上一页</el-button>
            <el-button @click="next">下一页</el-button>
            <span>Page: <span v-text="page_num"/> / <span v-text="page_count"/></span>
            <el-button icon="el-icon-plus" @click="addscale"/>
            <el-button icon="el-icon-minus" @click="minus"/>
            <el-button id="prev" @click="closeDialog">关闭</el-button>
          </div>
          <canvas id="the-canvas" class="canvasstyle"/>
        </div>
      </el-card>
    </el-dialog>
  </div>
</template>
<script>

// import PDFJS from 'pdfjs-dist'
// import workerSrc from 'pdfjs-dist/build/pdf.worker.entry'
// PDFJS.workerSrc = workerSrc
// PDFJS.GlobalWorkerOptions.workerSrc = require('pdfjs-dist/build/pdf.worker.min')
// PDFJS.GlobalWorkerOptions.workerSrc = 'pdfjs-dist/build/pdf.worker.entry'// './../../../node_modules/pdfjs-dist/build/pdf.worker.js'
import request from '@/utils/request'
import { Message } from 'element-ui'

export default {
  name: 'Pdf',
  props: {
    dialogSeeVisible: {
      type: Boolean,
      default: false
    },
    seeFileId: {
      type: Number,
      default: null
    }
  },
  data() {
    return {
      closeModel: false,
      clearable: false,
      urlPrefix: process.env.BASE_API,
      dialogTitle: '浏览技术文档',
      pdfurl: '',
      loading: false,
      pdfDoc: null, // pdfjs 生成的对象
      pageNum: 1, //
      pageRendering: false,
      pageNumPending: null,
      scale: 1.2, // 放大倍数
      page_num: 0, // 当前页数
      page_count: 0, // 总页数
      maxscale: 2, // 最大放大倍数
      minscale: 0.8// 最小放大倍数
    }
  },
  computed: {
    ctx() {
      const id = document.getElementById('the-canvas')
      return id.getContext('2d')
    }
  },
  created() {
    this.onOpen()
  },
  methods: {
    closeDialog(freshList) {
      const _this = this
      _this.pdfurl = ''
      _this.pdfDoc = null
      _this.pageNum = 1
      _this.pageRendering = false
      _this.pageNumPending = null
      _this.scale = 1.2
      _this.page_num = 0
      _this.page_count = 0
      // PDFJS.getDocument(_this.pdfurl).then(function(pdfDoc_) {
      //   _this.pdfDoc = pdfDoc_
      //   _this.page_count = _this.pdfDoc.numPages
      //   _this.renderPage(_this.pageNum)
      // })
      this.$emit('refreshValue', freshList)
    },
    onOpen() {
      const _this = this
      _this.loading = true
      request({ url2: '/document/info/preview/' + _this.seeFileId, method: 'get', url: 'http://localhost:8888/web/compressed.tracemonkey-pldi-09.pdf' }).then(
        function(value) {
          if (value.code === 200) {
            _this.pdfurl = _this.urlPrefix + '/' + value.data.fileVirtualPath
            _this.loading = false
            // 初始化pdf
            // PDFJS.getDocument(_this.pdfurl).then(function(pdfDoc_) {
            //   _this.pdfDoc = pdfDoc_
            //   _this.page_count = _this.pdfDoc.numPages
            //   _this.renderPage(_this.pageNum)
            // })
          } else {
            Message.error(value.message)
            _this.loading = false
            _this.closeDialog()
          }
        }
      )
    },
    renderPage(num) { // 渲染pdf
      const vm = this
      this.pageRendering = true
      const canvas = document.getElementById('the-canvas')
      // Using promise to fetch the page
      this.pdfDoc.getPage(num).then(function(page) {
        var viewport = page.getViewport(vm.scale)
        // alert(vm.canvas.height)
        canvas.height = viewport.height
        canvas.width = viewport.width
        // Render PDF page into canvas context
        var renderContext = {
          canvasContext: vm.ctx,
          viewport: viewport
        }
        var renderTask = page.render(renderContext)
        // Wait for rendering to finish
        renderTask.promise.then(function() {
          vm.pageRendering = false
          if (vm.pageNumPending !== null) {
          // New page rendering is pending
            vm.renderPage(vm.pageNumPending)
            vm.pageNumPending = null
          }
        })
      })
      vm.page_num = vm.pageNum
    },
    addscale() { // 放大
      if (this.scale >= this.maxscale) {
        return
      }
      this.scale += 0.1
      this.queueRenderPage(this.pageNum)
    },
    minus() { // 缩小
      if (this.scale <= this.minscale) {
        return
      }
      this.scale -= 0.1
      this.queueRenderPage(this.pageNum)
    },
    prev() { // 上一页
      const vm = this
      if (vm.pageNum <= 1) {
        return
      }
      vm.pageNum--
      vm.queueRenderPage(vm.pageNum)
    },
    next() { // 下一页
      const vm = this
      if (vm.pageNum >= vm.page_count) {
        return
      }
      vm.pageNum++
      vm.queueRenderPage(vm.pageNum)
    },
    queueRenderPage(num) {
      if (this.pageRendering) {
        this.pageNumPending = num
      } else {
        this.renderPage(num)
      }
    }
  }
}
</script>
<style scoped="" type="text/css">
.cpdf {
    top: 0;
    left: 0;
    background-color: rgba(0, 0, 0, .5);
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}
.center {
    text-align: center;
    height: 100%;
    overflow: auto;
    padding-top: 20px;
}
.contor {
    margin-bottom: 10px;
}
.button-group {
  float: right;
  margin-top: 10px;
  margin-bottom: 10px;
}
</style>
